Wednesday, February 17

Vitamin A is a group of organic compounds having similar biological and chemical activities.
Vitamin A is fat soluble vitamin and is essential for skin and vision care. Found in food items of animal origin Retinol is the main easily usable form of vitamin A.

Role in vision care

There are four kinds of photo pigments contained in human retina and they can store vitamin A compounds.
The retinol form has a special role in vision cycle. Rhodopsin, one of the retinal pigments is contained in rod cells of the retina.
Rhodopsin is needed for rod cells to detect small amounts of light and to see black and white. Deficiency leads to night blindness by inhibiting the reformation of rhodopsin.

Skin care and immunity care

In the retinoic acid form, Vitamin A, plays an important role in gene transcription.
It has active function in maintaining normal skin health and is a ingredient in skin care products.
Several immunity connected activities are stimulated by it . It primes up the white blood cells to increase the responses to antigens and has anti-viral activity. It has a positive role in preventing shrinkage of thymus gland.

Care in food habits to prevent vitamin A deficiency

Vitamin A deficiency can occur in adults and in children. Lack of care in consuming adequate quantities of the vitamin’s source foods can lead to primary or secondary levels of deficiency.
In new born, early weaning can lead to its deficiency unless care is taken to supplement it.
In developing countries, the high incidence of blindness, viral infections, and child mortality due lack of care in food habits leading to its deficiency.
In its deficiency the health of the skin, the elasticity of skin, hair, eyes, and immune system are affected. Further poor appetite, bone development abnormalities, and growth retardation are associated with insufficient intake of vitamin A.
Hyperkeratosis of skin, a goose pimple like look of the skin caused by excessive production of keratin that blocks hair follicles.
The skin becoming dry, scaly and rough and hair is lost.
With proper supplementation and skin care efforts normalcy of the skin can be achieved.
Night blindness and total loss of vision can occur in prolonged deficiency by setting in of the condition called Xerophthalmia where in cornea of the eye and conjunctiva undergo change.

Toxicity

Being fat soluble, vitamin A is absorbed and stored in body when in excess.
This excess presence can cause nausea, jaundice, pains and general physical and mental debility. In-take in the form of fruits and vegetables does not usually cause toxicity.
Supplements in the form of tablets and animal sources have to monitored and care must be taken to avoid overdose.

Sources of vitamin A

Animal source of this nutrient include eggs, liver, products of milk fat. Carrots, colored fruits like mangoes, spinach and red pepper are found to abound in vitamin A.

Vitiligo research on autologous melanocyte transplantation

Autologous melanocyte transplantation is being done by harvesting the normal melanocytes of the patient and transplanting them on to the affected skin area.
Very good results are being seen after 6 months with more than 90% success.
Further research is being done to improve on the bio-technology and the methodology for the transplantation.
Comparative evaluation of direct melanocyte transplant versus cultured melanocyte transplant is being made.

Vitiligo research on transplantation of melanocyte stem cells from hair follicle

In this new area of vitiligo research, ways to overcome the limitations in autologous melanocyte transplantation are being probed.
The limitations are in invasive tissue sampling and in cumbersome melanocyte extraction and culture procedures.
It is found that the hair follicle melanocytes apart from migrating up a hair follicle and giving it colour, are also capable of moving out to the surrounding melanin deficient epidermis.
Further it is found that undifferentiated melanocytes or stem cells are present in the outer root sheath of hair follicle.
The transplantation of these stem cells will repopulate the deficient skin with active melanocytes. This area requires further investigation and refining.

In the UVB therapy for leucoderma further strides have been made on the delivery of the rays. General exposure has been found to hasten the photo-aging of the skin.
In the latest method now being used and perfected is the apt selection of the required wavelength of Uv rays and its delivery mechanism.
Instead of generalised exposure of the affected area with the UVB rays, filters and methods are being evolved to only deliver UVB rays of 311[nm] and reduce the ill-effects of the full spectrum.
Further it is found that the melanocytes in the deeper perifollicular area are not affected by the causative factors of vitiligo.
These dormant melanocytes are selectively stimulated to proliferate and produce melanin.
The UVB rays are delivered by a optic fibre with control for the extent and duration of exposure.

Vitiligo research on genetic predisposition to the disease

Research is in progress to identify the deregulated genes giving rise to depigmentation.
About 800 genes have been identified for the hereditary affliction of this disorder.
The genetic association of this disorder with inflammatory diseases and autoimmune diseases is being probed.